1. Field of the Invention
This invention relates to pallets, and more particularly to improvements in slip pallets and slip pallet divider sheets.
2. Prior Art
Material handling apparatus for both consumer and industrial use is commonly designed for ease of storage and handling in a warehouse. Various kinds of containers for various kinds of goods are commonly arranged in a generally cubical array and are supported on a pallet. The array and pallet may then be lifted by a lift truck and stacked upon another array of containers for conservation of storage space.
Commonly used pallets are constructed from wood with two planar support surfaces separated by spaced rails. The support surfaces have the general size and shape of the array to be supported, and the pallet is about four inches thick. The pallet and array of containers are lifted and moved by inserting the forks of a forklift between the vertically separated support surfaces and the horizontally spaced spacer rails. Wood pallets are relatively expensive and have an undeterminable useful life. Furthermore, the thickness of these pallets takes up useful storage space and their weight adds to transportation expense.
These problems have been somewhat overcome by the development of slip pallets. A slip pallet is a relatively thin sheet of a material, such as chipboard, for supporting the array of containers. The array and slip pallet are lifted by gripping the edge of the pallet and holding it under tension while slipping a platen, or spatula-like member, of the lift truck under the pallet. The platen then lifts the array and pallet and transports them to a desired location where the slip pallet and the array are pushed off of the platen. Although slip pallets offer various advantages over common wooden pallets, some problems have been found in their use. For example, the edge of the slip pallet must be strong enough to be gripped by a gripping mechanism on the lift truck and held under tension while the platen of the lift truck is inserted underneath the pallet. If the pallet material is not sufficiently strong to support this tension, the gripped edge will tear away from the body of the pallet. This problem is particularly pronounced in the use of chipboard or cardboard slip pallets, especially when the chipboard or cardboard has been weakened by exposure to moisture. To overcome vulnerability to moisture and for various other reasons, it has been proposed to fabricate slip pallets from one piece of a relatively thin plastic material. For example, U.S. Pat. No. 3,776,145 discloses a slip pallet made from a pliable sheet of single thickness thermoplastic resin having a thickness of about 20 to about 125 mils. Flaps for gripping the slip pallet located about the edges of the pallet are defined by score lines in the thermoplastic resin. The flaps may then be bent about the score lines for gripping by the lift truck. These pallets do not suffer from moisture weakening as do those made from chipboard. The score lines, however, significantly weaken the strength of the pallet and may cause the flaps to tear off, especially when moderate to heavy loads are supported on the pallet. Furthermore, the normal position of the flaps is in the plane of the container support surface. After a flap has been bent upward for gripping by the mechanism, it will "spring back" to its normal position. Thus, the flaps will normally extend outward in the plane of the pallet causing damage to neighboring arrays of containers and requiring manual bending of the flaps prior to gripping by the gripping mechanism. For these reasons, the prior art slip pallets have proven to be unsatisfactory in certain respects.